As one of the causes of the global warming phenomenon, the greenhouse effect caused by CO2 is pointed out, and countermeasures thereagainst have also been a pressing need internationally in order to protect the environment of earth. As generation sources of CO2, in the fields of activity of all human beings which combust fossil fuels, the need for suppression of emission of CO2 tends to become stronger. Along with this, methods of bringing combustion gas of boilers into contact with amine-based absorption liquids, such as aqueous amine solutions and removing and recovering CO2 in the exhaust gas have been energetically studied for, for example, power generation facilities, such as thermoelectric power plants which use a large quantity of fossil fuels.
When CO2 is removed from exhaust gas using such absorption liquids, amine compounds are entrained in CO2-removed exhaust gas from which CO2 has been recovered. Also, in order to prevent a situation in which air pollution caused by the amine compounds occurs, it is necessary to reduce the emission amount of the amine compounds emitted together with the CO2-removed exhaust gas.
In the related art, PTL 1 discloses providing a plurality of washing sections which bring washing water into gas-liquid contact with CO2-removed exhaust gas from which CO2 has been absorbed and removed by gas-liquid contact with an absorption liquid, thereby recovering amine compounds entrained in the CO2-removed exhaust gas, and sequentially performing recovery processing of amines entrained in the CO2-removed exhaust gas in the plurality of main washing sections. As the washing water of this PTL 1, condensed water separated by condensing moisture included in CO2 in the processing of removing CO2 from the amine-based absorption liquid which has absorbed CO2, and regenerating the amine-based absorption liquid is used.
Additionally, in the related art, PTL 2 discloses providing a cooling section which cools CO2-removed exhaust gas from which CO2 has been absorbed and removed by the gas-liquid contact with an absorption liquid, and a contacting section which brings condensed water condensed in the cooling section into countercurrent contact with the CO2-removed exhaust gas. Moreover, PTL 2 discloses providing a washing section which brings washing water into gas-liquid contact with the CO2-removed exhaust gas from which CO2 has been absorbed and removed by gas-liquid contact with the absorption liquid, thereby recovering amine compounds entrained in the CO2-removed exhaust gas, and condensed water which has been condensed in a cooling tower which cools the exhaust gas before CO2 is recovered and is used as washing water.